1. Field of Invention
This invention relates to a grommet mounted to an automobile body panel of an automobile. In particular, this invention improves tightness between the grommet and a sound insulator secured to the automobile body panel.
2. Description of Related Art
A sound insulator to prevent a noise is secured to an automobile body panel that divides an engine compartment and a passenger compartment of an automobile. A wire harness extending between the engine compartment and the passenger compartment is mounted through a through hole in the automobile body panel and through an insertion hole into the sound insulator. When the wire harness is mounted, in order to ensure waterproofness and soundproofness between the engine compartment and the passenger compartment, a grommet disclosed in the Japanese Laid-Open Patent Publication No. 11-150837 is used, for example.
As shown in FIG. 5(A), the grommet 1 is provided with a small-diameter portion 2, in which the wire harness W/H is inserted, a large-diameter portion 3 having an engaging groove 3a to engage with a through hole Pa in an automobile body panel P, a seal member holding portion 4, in which seal member M can be filled, and a lip portion 5 that tightly contacts the area surrounding a peripheral edge of an insertion hole Sa of a sound insulator S from the outside (right side in FIG. 5(A)). Since the lip portion 5 closes the insertion hole Sa, noise is prevented from intruding through an area where the sound insulator S does not exist. Further, since the lip portion 5 is spaced from the large-diameter portion 3 and is independent from the large-diameter portion 3, the lip portion 5 is easily elastically extensible. Accordingly, in the event that the grommet 1 is mounted in the through hole Pa, when the entire grommet 1 is pushed into the through hole Pa from the engine compartment side E toward the passenger compartment side R, the lip portion 5 having a large-diameter does not become an obstacle.
However, as shown in FIG. 5(B), due to a mounting route of the wire harness W/H, the wire harness W/H might be mounted in a condition in which the wire harness W/H is bent and inclines in one direction away from the axial direction of the grommet 1. In this condition, the small-diameter portion 2 and the seal member holding portion 4 also incline with the wire harness W/H, and thus, the lip portion 5 is pressed in the same direction, as well. As a result, since the lip portion 5 only contacts at the area surrounding the peripheral edge of the insertion hole Sa from the outside, the lip portion 5 at the side opposite to the direction in which the wire harness W/H inclines might become separated from the peripheral edge of the insertion hole Sa, and thus, a gap X might occur. The gap X might become a factor that deteriorates soundproofness of the assembly.
Accordingly, the present invention is provided in view of the above-described problem, and an objective of the present invention is to prevent the lip portion from separating from the area surrounding the insertion hole of the sound insulator, and to close the lip portion tightly, even if the wire harness inserted into the grommet inclines and is bent when mounted.
To achieve the above and/or other goals, the present invention provides a grommet configured to be mounted in tight contact with a through hole in an automobile body panel and an insertion hole in a sound insulator secured on a surface of the automobile body panel. The grommet includes a small-diameter portion into which a wire harness is insertable and that is tightly contactable with the wire harness, and a large-diameter portion that radially extends from an outer peripheral surface of the small-diameter portion intermediate a length in an axial direction of the small-diameter portion. An outer peripheral surface of the large-diameter portion has an engaging groove that is engageable with an inner peripheral edge of the through hole. The grommet further includes an extending portion that extends past an end of the small-diameter portion along the axial direction, and a lip portion radially projecting from an outer peripheral surface of the extending portion. The lip portion is tightly contactable with an inner peripheral surface of the insertion hole in the sound insulator from inside.
Preferably, the lip portion includes a step portion at the peripheral edge of the lip portion. The step portion is elastically tightly engageable with the inner peripheral surface and an end face adjacent to a peripheral edge of the insertion hole.
According to the construction described above, since the lip portion (or step portion thereof) projects in a direction toward the insertion hole of the sound insulator and the step portion is provided to elastically tightly contact the inner peripheral surface as well as the outer surface of the sound insulator, the desired result of tightly closing the insertion hole can be achieved. Accordingly, when the wire harness inserted into the grommet is bent in one direction and to have a curved portion mounted, and as a result, the small-diameter portion is also bent in the one direction and the grommet tends to become slightly separated from the outer surface adjacent to the insertion hole in the sound insulator, the grommet maintains the insertion hole tightly closed due to the engagement of the step portion with the inner peripheral surface.
It is possible that the extending portion includes a seal member holding portion having a diameter larger than a diameter of the small-diameter portion and is configured to receive a seal member in an interior thereof, and the lip portion projects from an outer peripheral surface of the seal member holding portion. According to this construction, the seal member inserted into the seal member holding portion can improve waterproofness of the wire harness. In addition, when the wire harness is bent, the seal member holding portion contacts the inner peripheral surface of the insertion hole of the sound insulator via the step portion of the lip portion. Accordingly, the wire harness can be prevented from being bent excessively.
Preferably, a length between the engaging groove of the large-diameter portion and the step portion of the lip portion is shorter than a thickness of the sound insulator. When the large-diameter cylindrical portion engages with the through hole, the lip portion is pressed toward the engaging groove and elastically contacts the outer surface adjacent to the peripheral edge of the insertion hole in the sound insulator. According to this construction, the lip portion is mounted in the insertion hole of the sound insulator in a condition that a tensile force is applied in a direction closing the insertion hole (i.e. toward the engaging groove). Thus, the effectiveness of the lip portion to close the insertion hole against bending of the wire harness can be improved.